Wave retaining ring of a turbo machine assembly

Abstract

A turbo machine assembly comprises a first turbo machine component (58); a second turbo machine component (2); and a wave retaining ring (72) which frictionally secures the first turbo machine compone

Description

[0001] WAVE RETAINING RING OF A TURBO MACHINE ASSEMBLY

[0002] The present invention relates to a turbo machine assembly, compressor housing assembly, compressor, turbo machine and associated methods.

[0003] Compressors receive fluid, such as air, via an inlet, and exhaust pressurised fluid via an outlet. Provided between the inlet and outlet is a compressor wheel, supported for rotation on a shaft. The compressor wheel does work on the fluid, by virtue of the shaft being driven, to increase the pressure of the fluid.

[0004] Compressor covers or compressor housing assemblies are known components that generally surround the compressor wheel. Compressor covers may, for centrifugal compressors, also define a volute which is located between the compressor wheel and the outlet.

[0005] One use of a compressor is as part of a turbo machine, such as a turbocharger. Turbochargers are well known devices for supplying air to the intake of an internal combustion engine at pressures above atmospheric pressure (boost pressures). A conventional turbocharger comprises an exhaust gas driven turbine wheel mounted on a rotatable shaft within a turbine housing. Rotation of the turbine wheel rotates the compressor wheel mounted on the other end of the shaft within the compressor cover. The compressor wheel delivers compressed air to the intake manifold of the engine, thereby increasing engine power.

[0006] The turbocharger shaft is conventionally supported by journal and thrust bearings, including appropriate lubricating systems, located within a central bearing housing connected between the turbine and compressor.

[0007] Some compressors include vanes which are located in an outlet passageway downstream of the compressor wheel. The vanes help to guide liquid compressed by the compressor towards the compressor outlet to thereby increase the efficiency of the compressor. In some known compressors, the vanes are provided on a diffuser vane ring. The diffuser vane ring is secured to a compressor housing using a relatively complicated and costly arrangement of fasteners and seals to form a compressor housing arrangement. There exists a need to provide an alternative way of securing turbo machine components (such as a compressor housing and diffuser vane ring) together, which overcomes disadvantages that exist with known ways of securing turbo machine components together, whether mentioned in this document or otherwise.

[0008] According to a first aspect of the invention there is provided a turbo machine assembly comprising: a first turbo machine component; a second turbo machine component; and a wave retaining ring which frictionally secures the first turbo machine component to the second turbo machine component via clamping of the wave retaining ring between a first clamp surface of the first turbo machine component and a second clamp surface of the second turbo machine component; wherein the first turbo machine component is rotatable relative to the second turbo machine component about a first axis; wherein an axial height of the first clamp surface changes as a function of angular position about the first axis; and wherein an axial spacing between a portion of the second clamp surface and the first clamp surface changes as the rotational position of the first turbo machine component relative to the second turbo machine component changes.

[0009] Use of a wave retaining ring to secure the first and second turbo machine components together provides a relatively straightforward and cost effective way of securing the turbo machine components together. Furthermore, being able to clamp the components together with wave retaining ring by rotating the first turbo machine component relative to the second turbo machine component provides a very simple method of installing the wave retaining ring to secure the first and second turbo machine components together by clamping.

[0010] The wave retaining ring may comprise a first anti-rotation feature which co-operates with a corresponding second anti-rotation feature of the second turbo machine component to substantially prevent rotation of the wave retaining ring relative to the second turbo machine component, when the first turbo machine component is rotated relative to the second turbo machine component.

[0011] The use of co-operating anti-rotation features may make the process of clamping the wave retaining ring between the first and second clamp surfaces more straightforward. The first anti-rotation feature may comprise a first projection which is received by a corresponding first recess of the second anti-rotation feature.

[0012] The first anti-rotation feature may comprise a first recess which receives a corresponding first projection of the second anti-rotation feature.

[0013] The first projection and first recess may extend generally axially.

[0014] The first projection and first recess may extend generally radially.

[0015] The first turbo machine component may comprise a tool engagement feature which is configured, in use, to engage with a rotation tool and transform a rotation of the rotation tool into rotation of the first turbo machine component relative to the second turbo machine component about said first axis.

[0016] The wave retaining ring may be generally annular about a central spring axis.

[0017] An axial height of the wave retaining ring may oscillate as a function of angular position about the spring axis, such that the wave retaining ring has one or more peak portions in which said axial height of the wave retaining ring is a maximum.

[0018] The axial height of the first clamp surface may change as a function of angular position about the first axis and comprises one or more trough portions corresponding in number to said one or more peak portions.

[0019] In an unclamped position of the first turbo machine component relative to the second turbo machine component, each of the one or more peak portions may locate within a corresponding trough portion of the first clamp surface.

[0020] An axial spacing between said portion of the second clamp surface and the first clamp surface may be an unclamped spacing sufficient to accommodate the axial height of the portion of the wave retaining ring located axially between the portion of the second clamp surface and the first clamp surface. In a clamped position of the first turbo machine component relative to the second turbo machine component, in which, in relation to the unclamped position, the first turbo machine component is rotated about the first axis relative to the second component, each of the one or more peak portions of the wave retaining ring may not be located within a corresponding trough portion of the first clamp surface and an axial spacing between said portion of the second clamp surface and the first clamp surface may be a clamped spacing, less than said unclamped spacing, such that the first and second clamp surfaces may apply an axial load to the wave retaining ring which may axially compress the wave retaining ring so that it may have a working axial height which is less than a relaxed axial height of the wave retaining ring when the wave retaining ring does not have an axial load applied to it.

[0021] Each trough portion of the first clamp surface may adjoin a corresponding circumferentially extending ramp portion of the first clamp surface.

[0022] Each ramp portion of the first clamp surface may adjoin a corresponding circumferentially extending summit portion of the first clamp surface.

[0023] Each summit portion may have an axial height which is greater than the axial height of the trough portion of the first clamp surface to which said summit portion corresponds.

[0024] Each ramp portion of the first clamp surface may be located circumferentially between the corresponding trough portion of the first clamp surface and the corresponding summit portion of the first clamp surface.

[0025] The first turbo machine component may be a compressor outlet diffuser vane ring and the second turbo machine component may be a compressor housing. The turbo machine assembly may be a compressor housing assembly. According to another aspect, there is provided a turbo machine comprising a compressor having a compressor housing arrangement including the features of the first aspect of the invention.

[0026] According to a second aspect of the invention there is provided a turbo machine assembly wave retaining ring, wherein the wave retaining ring is generally annular about a central spring axis and wherein an axial height of the wave retaining ring oscillates as a function of angular position about the spring axis, wherein the wave retaining ring comprises a first anti-rotation feature for co-operating with a corresponding second anti-rotation feature of a turbo machine component to substantially prevent relative rotation between the wave retaining ring and the turbo machine component, and wherein the first anti-rotation feature comprises a generally radial protrusion and / or a generally axial protrusion.

[0027] According to a third aspect of the invention there is provided a method of assembling a turbo machine assembly, the turbo machine assembly comprising: a second turbo machine component having a second clamp surface; a first turbo machine component rotatable relative to the second turbo machine component about a first axis, the first turbo machine component including a first clamp surface having an axial height which changes as a function of angular position about the first axis; and a wave retaining ring; wherein the method comprises: locating the wave retaining ring between the first clamp surface and second clamp surface; rotating the first turbo machine component relative to the second turbo machine component to change the rotational position of the first turbo machine component relative to the second turbo machine component and thereby reduce an axial spacing between a portion of the second clamp surface and the first clamp surface, and hence clamp the wave retaining ring between the first turbo machine component and second turbo machine component and thereby frictionally secure the first turbo machine component to the second turbo machine component.

[0028] The turbo machine may be a turbocharger. The turbo machine may be a fuel cell compressor. The turbocharger may be a fixed geometry turbocharger. The turbocharger may be a variable geometry turbocharger.

[0029] The turbocharger may form part of an engine arrangement. The engine arrangement may be part of a vehicle, such as an automobile. The engine arrangement may have a static application, such as in a pump arrangement or in a generator.

[0030] The turbocharger may comprise a turbine which is connected, directly or indirectly, to the compressor. The turbine may comprise a turbine wheel, the turbine wheel being supported on the same shaft as the compressor wheel. An exhaust gas flow may be used to drive the turbine wheel so as to drive rotation of the compressor wheel. The compressor may be secured to the turbine via a bearing housing.

[0031] The downstream outlet of the compressor may be in fluid communication with an inlet manifold of cylinders of an engine or with an inlet manifold of a fuel cell. The compressor may be used to provide a boost pressure to the engine. An engine comprising the turbocharger may provide improved performance over an engine without a turbocharger, owing to exhaust gas exhausted from the cylinders being used to drive the turbine wheel and so compressor wheel. In other words, otherwise wasted energy in the exhaust flow is used to pressurise air which is used in the combustion cycle.

[0032] The optional and / or preferred features for each aspect of the invention set out herein are also applicable to any other aspects of the invention.

[0033] Specific embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

[0034] Figure 1 is a schematic axial cross-section through a known variable geometry turbocharger;

[0035] Figure 2 is a schematic cross-sectional side view of a known compressor housing;

[0036] Figure 3 is a schematic cross-sectional side view of a portion of a known turbocharger;

[0037] Figure 4 is a schematic cross-sectional side view of a portion of a turbocharger including a compressor housing assembly according to an embodiment of the invention;

[0038] Figure 5 shows schematic cross-sectional side views of a portion of the compressor housing assembly shown in figure 4, including a view in which a diffuser vane ring is in an unclamped configuration, and a view in which the diffuser vane ring is in a clamped configuration; Figure 6 is a schematic depiction of the diffuser vane ring of the compressor housing assembly shown in figures 4 and 5, including a plan view of the diffuser vane ring and a side view of a portion of the diffuser vane ring;

[0039] Figure 7 is a schematic depiction of a side view of the wave retaining ring and portions of the diffuser vane ring and compressor housing, as shown in Figures 4 to 6, wherein the circumference of these structures has been laid flat, wherein the upper view shows an unclamped configuration and the lower view shows a clamped configuration;

[0040] Figure 8 is a schematic perspective view of two wave retaining rings in accordance with embodiments of the present invention, which include anti-rotation features.

[0041] Referring to Figure 1, this illustrates a known variable geometry turbocharger comprising a housing comprised of a variable geometry turbine housing 1 and a compressor housing 2 (sometimes referred to as a compressor ‘shroud’ or compressor cover) interconnected by a central bearing housing 3. A turbocharger shaft 4 extends from the turbine housing 1 to the compressor housing 2 through the bearing housing 3. A turbine wheel 5 is mounted on one end of the shaft 4 for rotation within the turbine housing 1, and a compressor wheel 6 is mounted on the other end of the shaft 4 for rotation within the compressor housing 2. The shaft 4 rotates about turbocharger axis 4a on bearing assemblies located in the bearing housing 3. In between the compressor housing 2 and the bearing housing 3 is a diffuser plate 2a (or seal plate) which is recessed to accommodate an inboard portion of the compressor wheel 6, i.e. a portion nearest to the bearing housing 3, to increase the efficiency of the compressor stage.

[0042] The turbine housing 1 defines an inlet volute 7 to which gas from an internal combustion engine (not shown) is delivered. The exhaust gas flows from the inlet volute 7 to an axial outlet passage 8 via an annular inlet passage 9 and the turbine wheel 5. The inlet passage 9 is defined on one side by a face 10 of a radial wall of a movable annular wall member 11, commonly referred to as a “nozzle ring”, and on the opposite side by an annular shroud 12 which forms the wall of the inlet passage 9 facing the nozzle ring 11. The shroud 12 covers the opening of an annular recess 13 in the turbine housing 1. The nozzle ring 11 supports an array of circumferentially and equally spaced inlet vanes 14 each of which extends across the inlet passage 9. The vanes 14 are orientated to deflect gas flowing through the inlet passage 9 towards the direction of rotation of the turbine wheel 5. When the nozzle ring 11 is proximate to the annular shroud 12, the vanes 14 project through suitably configured slots in the shroud 12, into the recess 13.

[0043] The position of the nozzle ring 11 is controlled by an actuator assembly of the type disclosed in US 5,868,552. An actuator (not shown) is operable to adjust the position of the nozzle ring 11 via an actuator output shaft (not shown), which is linked to a yoke 15. The yoke 15 in turn engages axially extending actuating rods 16 that support the nozzle ring 11. Accordingly, by appropriate control of the actuator (which may for instance be pneumatic or electric), the axial position of the rods 16 and thus of the nozzle ring 11 can be controlled. The speed of the turbine wheel 5 is dependent upon the velocity of the gas passing through the annular inlet passage 9. For a fixed rate of mass of gas flowing into the inlet passage 9, the gas velocity is a function of the width of the inlet passage 9, the width being adjustable by controlling the axial position of the nozzle ring 11. Figure 1 shows the annular inlet passage 9 fully open. The inlet passage 9 may be closed to a minimum by moving the face 10 of the nozzle ring 11 towards the shroud 12.

[0044] The nozzle ring 11 has axially extending radially inner and outer annular flanges 17 and 18 that extend into an annular cavity 19 provided in the turbine housing 1. Inner and outer sealing rings 20 and 21 are provided to seal the nozzle ring 11 with respect to inner and outer annular surfaces of the annular cavity 19 respectively, whilst allowing the nozzle ring 11 to slide within the annular cavity 19. The inner sealing ring 20 is supported within an annular groove formed in the radially inner annular surface of the cavity 19 and bears against the inner annular flange 17 of the nozzle ring 11. The outer sealing ring 20 is supported within an annular groove formed in the radially outer annular surface of the cavity 19 and bears against the outer annular flange 18 of the nozzle ring 11.

[0045] Gas flowing from the inlet volute 7 to the outlet passage 8 passes over the turbine wheel 5 and as a result torque is applied to the shaft 4 to drive the compressor wheel 6. Rotation of the compressor wheel 6 within the compressor housing 2 pressurises ambient air present in an air inlet 22 and delivers the pressurised air to an air outlet volute 23 from which it is fed to an internal combustion engine (not shown).

[0046] Figure 2 shows a prior art compressor housing 2 for a compressor. The compressor housing comprises an inlet 22, an impeller chamber 6a and an outlet which includes outlet volute 23. The inlet 22 comprises a baffle 24, an outer wall 26, an end cap 28 and a retaining ring 30. The baffle 24 and outer wall 26 are integrally formed and may be said to define a compressor body, from which the end cap 28 and retaining ring 30 are separable. The baffle 24 is generally tubular and extends axially along a compressor axis 32 (which, when the compressor forms part of a turbocharger, such as that shown in Figure 1 , may be the same as the turbocharger axis 4a). The centre of the baffle 24 defines an inlet passage 34 configured to provide fluid to the impeller chamber 6a, and, in particular, to an inducer of a centrifugal impeller (or compressor wheel) contained within the impeller chamber 6. The outer wall 26 concentrically and circumferentially surrounds the baffle 24. The outer wall 26 is spaced apart from the baffle 24 to define a generally annular recirculation passage 36 therebetween. The end cap 28 is formed as a generally frusto-conical piece of thin-walled material. The end cap 28 comprises a radially outer edge that is received within a circumferentially extending stepped groove 38 of the outer wall 26. The retaining ring 30 is received within the stepped groove 38 to hold the end cap 28 in position within the inlet 22.

[0047] The impeller chamber 6a is defined in part by an impeller chamber surface 38. The impeller chamber surface 38 closely conforms to the geometry of the impeller so as to contain the working fluid so that is compressed by the action of the impeller blades. Accordingly, the impeller chamber surface 38 is generally trumpet-shaped. The baffle 24 comprises a first fluid communication passage 40 that is defined by a circumferential slot extending between the recirculation passage 36 and the impeller chamber surface 38. The first fluid communication passage 40 is positioned so that, during use, it is downstream of the leading edges of the blades of the impeller (not shown in Figure 2).

[0048] A second fluid communication passage 42 extends between the recirculation passage 36 and the inlet passage 34. The second fluid communication passage 42 is defined by an annular gap between the end cap 28 and a distal end of the baffle 24 which are spaced apart along the compressor axis 32 by a small amount. The second fluid communication passage 42 is positioned upstream of the leading edges of the blades of the impeller during use.

[0049] The baffle 24 is supported by three identical struts 44 that extend axially along the compressor axis 32. The struts 44 extend from a proximal end of the recirculation passage 36 relative to the impeller chamber 6a across the first fluid communication passage 40 so as to mechanically support the baffle 24 within the compressor inlet 22. The struts 44 are equispaced about the compressor axis 32 so that each strut 44 is approximately 120° apart from the next strut. The configuration of the struts is discussed only to provide useful background information for understanding the invention - it is not of particular importance to the inventive concept of the present application.

[0050] During use, working fluid may enter the recirculation passage 36 from the impeller chamber 6a via the first fluid communication passage 40. Accordingly, the first fluid communication passage 40 may be considered to be an inlet of the recirculation passage 36. Since the working fluid entering the recirculation passage 36 has been to some degree compressed by the action of the impeller, the working fluid in the recirculation passage 36 has a higher pressure than the working fluid in the inlet passage 34. As a result, the working fluid leaves the recirculation passage 36 and reenters the inlet passage 34 via the second fluid communication passage 42. The second fluid communication passage 42 may therefore be considered to be an outlet of the recirculation passage 36.

[0051] The above-described structure (baffle, end cap, retaining ring, recirculation passage, first and second fluid communication passages) is an example of a so-called “map width enhancement” structure. By allowing a small amount of compressed fluid to escape from the impeller, for a given pressure ratio, the minimum mass flow required to avoid surge events can be reduced, and hence the “width” of the operating map of the compressor 2 is said to be enhanced. Other known compressors may not have a map width enhancement structure and these features may be omitted.

[0052] The outlet comprises a volute portion 23 and an exit portion. The volute portion 23 is a generally scroll-shaped part of the outlet that is configured to receive working fluid that has been compressed by the impeller and to guide the working fluid circumferentially around the compressor axis 32 and radially outwards from the compressor axis 32 in a spiral-like motion. The exit portion is a generally pipe-like section of the outlet that receives the working fluid from the volute portion 23. The exit portion comprises a mounting flange configured for connection to a downstream pipe network, for example in an internal combustion engine system.

[0053] The baffle 24 defines an outer surface 46 on a radially outer side relative to the compressor axis 32 and an inner surface 48 on a radially inner side relative to the compressor axis 18. In the depicted embodiment, the struts 44 are integrally formed with the baffle 24. However, in alternative embodiments the struts 44 may be formed separately to the baffle 24 and attached thereto via the outer surface 46. It will be appreciated that the struts 44 must form a mechanical interface with the outer surface 46 of the baffle 24 to enable the struts 44 to mechanically support the baffle 24 within the compressor inlet 22.

[0054] When fluid, such as air, enters the compressor 2 via the inlet 22, it first passes through an inlet passage 34. The fluid then reaches the compressor wheel 6, passing over blades of the compressor wheel 6. Whilst the compressor wheel 6 rotates, work is done on the fluid. As best seen in Figure 3, which is a cross-section through a portion of a compressor housing 2 and bearing housing 3 of another known turbocharger, the fluid then passes through a passage 50. The passage 50 is a generally radial annular passage. The passage 50 interconnects the impeller chamber 6a (and hence inlet passage 34 and inlet 22) with the volute 23 (and so downstream outlet). More detail regarding the passage 50 is provided below.

[0055] After passing generally radially along the passage 50, the fluid enters the volute 23. The volute 23 has a cross-sectional area which increases, generally linearly, around the central axis 32, so as to recover pressure from the flow. The pressurised fluid then exits the compressor via the downstream outlet.

[0056] Turning to the passage 50, the passage 50 is defined, at least in part, by a first wall 52 and a second wall 54. The first and second walls 52, 54 are generally annular in that they extend around the central axis 32. The passage 50, as mentioned above, extends in a generally radial direction relative to the central axis 32. That is to say, in the illustrated embodiment, the passage 50 extends generally perpendicularly to the central axis 32. In other embodiments, the passage may extend at any one of a range of different angles relative to the central axis 32. The passage 50 may be described as a diffuser, or a diffuser passage. This may be because in the passage 50 the velocity of the fluid is reduced so as to generally decrease the total pressure of the flow whilst increasing the static pressure of the flow (otherwise known as recovering static pressure in the flow). In other arrangements the passage may generally diverge moving radially outwardly of the central axis.

[0057] A plurality of vanes, a portion of one of which is labelled 56, extend across the passage 50. That is to say, the plurality of vanes extend between the first and second walls 52, 54. Each of the plurality of vanes have the shape of an aerofoil and therefore have a pressure side 56a and a suction side 56b. The pressure side is generally proximate the compressor wheel 6 (as compared to the suction side). Put another way, the pressure side is the side of the vane 56 which is closest to the central axis 32. The suction side is generally distal to compressor wheel 6 (as compared to the pressure side).

[0058] As shown in Figure 3, the second wall 54 forms part of a plate member 58, which may also be referred to as a diffuser vane ring. Plate member 58 is generally annular in shape. A radially inner end 54a of the second wall 54, and so of the plate member 58, is proximate a radially outer tip of the compressor wheel 6. A radially outer end 54b of the second wall 54, and so of the plate member 58, is distal to the compressor wheel 6. The radially outer end 54b of the second wall 54 defines, in part, the volute 23. The volute 23 is also defined by a volute wall 23a. The volute wall 23 extends between the radially outer end of the 54b of the second wall and a radially outer end of the first wall 52.

[0059] In Figure 3 the compressor housing 2 engages the plate member 58 by way of a top portion of each of the vanes 56 abutting the first wall 52 and an outer circumference of the plate member 58 being received in a close-fitting relationship within a circular plate aperture, defined by wall 60, of the compressor housing 2. A plurality of fasteners, only one of which, indicated by 62, is visible in the figure, is used to secure the plate member 58 to the compressor housing 2. A radially inner flange 58a of the plate member 58 is received within an annular plate recess 64 of the bearing housing 3 to locate the plate member 58 and hence compressor housing 2 relative to the bearing housing 2. As previously mentioned, the plate member 58 is received by the compressor housing 2 and secured in place by a number of fasteners 62. In one particular example, the plurality of fasteners is three screws and associated washers circumferentially distributed around the plate number 58 and received in corresponding threaded portions of the compressor housing 2. However, in other examples, any appropriate number and type of fastener can be used. The compressor housing 2 and plate member 58 fastened to the compressor housing 2 maybe referred as a compressor housing assembly. The compressor housing assembly is mounted to the bearing housing 3 and secured thereto be a V-band 68 which clamps circumferential flanges 2a and 3a of the compressor housing and bearing housing 3, respectively, together. A C- seal 66 is located between the bearing housing 3 and lower face 58b of the plate member 58 so as to ensure that the plate member 58 (and, in particular the vanes 56 of the plate member 58) is urged axially against the compressor housing 2 (and, in particular, first wall 52) when the compressor housing assembly is secured to the bearing housing 3.

[0060] The present design of turbocharger, and, in particular, compressor housing assembly, is relatively complex. There are many components involved (fasteners, associated washers, and C-seal) which may be relatively expensive. For example, due to the mechanical and thermal properties required, the C-seal maybe made from Inconel, which is a relatively costly alloy. Finally, the requirement to compress the C-seal in order to urge the plate member against the compressor housing means that the joint capability of the compressor 2 bearing housing joint is reduced as clamp load is lost compressing the C-seal.

[0061] It may be desirable to provide a compressor housing assembly which does not suffer from disadvantages of prior art compressor housing assemblies, whether discussed herein or otherwise. In addition, it may be desirable to provide an alternative compressor housing assembly.

[0062] Figure 4 shows a schematic cross-section through a portion of a turbocharger including a compressor housing assembly in accordance with an embodiment of the present invention. Features of the turbocharger within figure 4 which are equivalent to those of the known turbocharger previously discussed have been given the same reference numerals. The following description focuses only on the differences between the turbocharger discussed in relation to Figures 1 to 3 and that of the present invention.

[0063] The compressor housing assembly shown in Figure 4 differs from that previously discussed in that the compressor housing 2 includes a circumferentially extending groove 70. The groove 70 may be said to take the form of a recess within the wall 60 of the compressor housing which defines the circular plate aperture.

[0064] A wave retaining ring 72 is received within the recess 70 and extends radially inboard (with respect to the central axis 32) so as to engage with a bottom face 58b of the plate member 58 and secure the plate member 58 to the compressor housing 2. The compressor housing assembly constitutes a turbo machine assembly. The turbo machine assembly includes a first turbo machine component (in the present embodiment a compressor outlet diffuser vane ring (or plate member 58)) and a second turbo machine component (in the present embodiment a compressor housing 2).

[0065] The wave retaining ring 72 frictionally secures the compressor outlet diffuser vane ring 58 to the second turbo machine component (compressor housing 2) via clamping of the wave retaining ring 72 between a first clamp surface 74 of the first turbo machine component, and a second clamp surface 70a of the second turbo machine component - in this example the second clamp surface 70a of the second turbo machine component (compressor housing 2) is the generally annular wall 70a which defines a portion of the groove 70 within the compressor housing 2.

[0066] It will be appreciated that the wave retaining ring 72 is clamped between the first clamp surface 74 of the plate member 58, and second clamp surface (annular surface 70a of the groove 70 of the bearing housing 3). Such clamping of the wave retaining ring 72 results in the wave retaining ring 72 exerting a generally axial reaction force which is incident on both the first clamp surface 58b of the first turbo machine component 58 and the second clamp surface 70a of the second turbo machine component (the annular surface 70a of the compressor housing 2). The reaction force exerted on the first turbo machine component (ring plate 58) and second turbo machine component (compressor housing 2) results in a frictional force being exerted by the wave retaining ring 72 on each of the first turbo machine component and second turbo machine component, thereby securing the first turbo machine component to the second turbo machine component.

[0067] Use of a wave retaining ring to secure the first turbo machine component (plate number 58) to the second turbo machine component (compressor housing 2) is much less complex than the previously discussed prior art method of securing these components together. This is because it requires fewer components (a single wave retaining ring compared to fasteners, washers and C-seals) and less expensive (as the wave retaining ring is less costly than the fasteners and C-seal).

[0068] A wave retaining ring is a ring which is used to retain one component relative to another. A key feature of a wave retaining ring is that, instead of it being generally flat or planar, as its name suggests, it has a profile which can be likened to a transverse wave - whereby a height (in particular, a height measured parallel to an axis around which the retaining ring extends) of the retaining ring oscillates transversely (i.e. perpendicular to) the circumferential path of the retaining ring. In other words, if the retaining ring is thought of as a body which extends along a circumferential path about a central axis, height of the wave retaining ring relative to a plane, which is perpendicular to the central axis surrounded by the wave retaining ring and which is located at a fixed position along said axis, changes as a function of position along the circumference of the wave retaining ring. The height of the wave retaining ring along the circumference maybe said to oscillate as it increases and decreases as you move around the circumference of the wave retaining ring. Portions of each oscillation of the wave retaining ring which have a maximum height in a particular direction along the axis may be referred to as crests or crest portions of the wave retaining ring. Portions of each oscillation of the wave retaining ring which have a minimum height in said particular direction along the axis may be referred to as troughs or trough portions of the wave retaining ring.

[0069] Some wave retaining rings may oscillate in a manner such that the height of the wave retaining ring as a function of circumferential position undergoes an integer number of oscillations in a complete orbit or rotation of the circumference. Furthermore, in the present example, the height of the peaks of each oscillation of the wave retaining ring is the same; and the height of the trough of each oscillation of the wave retaining ring is the same. In other embodiments the characteristics of the wave retaining ring maybe different. For example, the wave retaining ring may have a non-integer number of oscillations in the entire circumference of the wave retaining ring, the oscillations of the wave retaining ring maybe different and the heights of the crests and / or troughs of each oscillation within the wave retaining ring maybe different.

[0070] The wave retaining ring 72 has a relaxed state in which it has a total axial height (an axial distance between the portion of the wave retaining ring which is located furthest along the axis in a first direction and the portion of the wave retaining ring which is located the furthest along the axis in a second direction along the axis, opposite to the first direction) that is a relaxed axial height. When the wave retaining ring 72 is axially compressed, such that the total axial height of the wave retaining ring is less than the relaxed axial height of the wave retaining ring, the wave retaining ring is said to be in a compressed state. When a wave retaining ring is axially compressed, in the manner of a spring, as is well known, the wave retaining ring exerts an opposing axial force which is approximately proportional to the amount axial compression of the wave retaining ring relative to its relaxed state.

[0071] As can be seen in the embodiment in Figure 4, the wave retaining ring 72 is compressed between the bottom surface 58b of the plate member 58 and a generally circumferential surface 70a of the compressor housing 2 which defines the groove 70. In light of this the wave retaining ring 72 is in a compressed state and exerts a generally axial force on both the compressor housing 2 and plate member 58. The axial force exerted on the plate member 58 and compressor housing 2 by the wave retaining ring 72 also results in a frictional force between the plate member 58, retaining ring 72 and compressor housing 2. It follows that not only does the wave retaining ring 72 exert generally axial force on the plate member 58 relative to the compressor housing 2, which urges the plate member 58 (and in particular the vanes 56 of the plate member 58) axially into abutment with the first wall 52 defined by the compressor housing 2, but also the wave retaining ring exerts a frictional force on both the plate member 58 and compressor housing 2 which acts to resist relative rotation (about the central axis 32) of the plate member 58 relative to the compressor housing 2.

[0072] In the above discussion, the plate member 58 (which may also be referred to as a compressor outlet diffuser vane ring) may be considered to be a first turbo machine component, which includes a first clamp surface in the form of the bottom surface 58b of the plate member 58; and the compressor housing 2 may be considered to be a second turbo machine component which has a second clamp surface that takes the form of the surface 70a of the groove 70 of the compressor housing 2. As such, it can be said that the wave retaining ring 72 frictionally secures the first turbo machine component 58 to the second turbo machine component 2 via clamping of the wave retaining ring 72 between the first clamp surface 58b of the first turbo machine component 58 and the second clamp surface 70a of the second turbo machine component 2.

[0073] As previously discussed, the first turbo machine component 58 is rotatable relative to the second turbo machine component 2 about the central axis 32. This is because the plate member 58 is generally annular and is received within a circular plate aperture defined by the wall 60 of the compressor housing 2.

[0074] Figure 7 shows two separate corresponding views of the wave retaining ring 72, first clamp surface 58b and second clamp surface 70a.

[0075] In the upper view the wave retaining ring 72 is located between the first turbo machine component (plate member 58) and the second turbo machine component (compressor housing 2) such that the wave retaining ring 72 is in its relaxed configuration.

[0076] The lower view in Figure 7 shows the wave retaining ring 72 being clamped between the first turbo machine component (plate member 58) and second turbo machine component (compressor housing 2), and, in particular, such that the wave retaining ring is clamped between the first clamp surface 58b and the second clamp surface 70a. In this way the wave retaining ring 72 is axially compressed and therefore secures the first turbo machine component 58 relative to the second turbo machine component 2.

[0077] Each of the upper and lower views of Figure 7 show a schematic view of the surface 70a of the compressor housing, the retaining ring 72 and the rear surface 58b of the plate member 58 such that the circumferential nature of these structures about the central axis 32 have been ‘laid flat’ on the page. The central axis 32 lies parallel to the plane of the page and is generally perpendicular to the surface 70a. As previously discussed, the lower surface 58b of the plate member 58 constitutes a first clamp surface. As can be seen from the Figures, the axial height indicated by H of the first clamp surface (where the axial height is a distance along the central axis 32 measured relative to a given datum position) changes as a function of angular position about the central axis.

[0078] Given that, as previously discussed, Figure 7 shows the circumference of the relevant structures about the central axis laid flat on the page, it will be appreciated that the position of the relevant structures left to right (or vice versa) on the page, is equivalent to an angular location of the relevant structures about the axis.

[0079] The bottom view of Figure 7 shows a rotation of plate member 58 about the central axis 32 in the direction R by an angular distance 0. It can be seen that, by rotating the plate member 58 (and hence first clamp surface 58b) relative to the second turbo machine component (compressor housing 2), the axial spacing between a portion P of the second clamp surface 70a and the first clamp surface 58b is reduced from that indicated by A to that indicated by B. That is to say, as the rotational position of the first turbo machine component 58 relative to the second turbo machine component changes (for example the first clamp surface 58b is rotated in the direction R by an angle 0 relative to the second clamp surface 70a) an axial spacing between a portion of the second clamp surface 70a and the first clamp surface 58b changes (for example reduces from the spacing indicated by A in the upper portion of Figure 7 to the spacing indicated by B as shown in the lower portion of Figure 7).

[0080] As previously discussed, rotation of the plate member 58 relative to the compressor housing 2 will result in the axial spacing between the clamp surfaces of these components in a particular position decreasing. When the wave retaining ring 72 is received between the first and second clamp surfaces 58b, 70a and the axial spacing between the clamp surfaces is reduced due to relative rotation between the plate member 58 and compressor housing 2, the wave retaining ring 72 located between the first and second turbo machine components 58, 2 will be axially compressed. As previously discussed, axial compression of the wave retaining ring will result in the wave retaining ring 72 exerting a force on each of the plate member 58 and compressor housing 2 which secures the turbo machine component together. Figure 5 shows two schematic views of a portion of a turbo machine in accordance with the embodiment of the present invention. In particular, figure 5 shows a compressor housing arrangement comprising compressor housing 2 and plate member 58. The view on the left shows the plate member 58 in an unclamped position relative to the compressor housing 2 such that the wave retaining ring 72 is in a relaxed state. In the view on the right, the plate member 58 has been rotated relative to the compressor housing 2 (for example in a direction R by an angular distance 0 as shown in Figure 7) to a clamped position. It can be seen that the wave retaining ring 72 has been axially compressed between the first clamp surface 58b and second clamp surface so as to clamp the plate member 58 to the compressor housing 2 in the manner previously discussed.

[0081] So that the wave retaining ring 72 does not rotate with the plate member 58 when the plate member is rotated relative to the compressor housing 2, the wave retaining ring may be provided with a first anti-rotation feature which cooperates with a corresponding second anti-rotation feature of the compressor housing to substantially prevent rotation of the wave retaining ring 72 relative to the compressor housing when the plate member 58 is rotated relative to the compressor housing 2. Preventing the wave retaining ring from rotating when the plate member 58 is rotated ensures that the rotation of the plate member 58 relative to the compressor housing 2 achieves the required axial compression of the wave retaining ring 72.

[0082] Figure 8 shows two examples of wave retaining ring 72 which include anti-rotation features.

[0083] The view on the right shows a first anti-rotation feature 72c of the wave retaining ring 72, the anti-rotation feature 72c comprising a first projection which is received by a corresponding first recess (not shown) of the second anti-rotation feature of the compressor housing 2. The first projection and first recess extend generally radially - i.e. perpendicular to the central / spring axis 32.

[0084] The view on the left shows a first anti-rotation feature 72d of the wave retaining ring 72, the anti-rotation feature 72d comprising a first projection which is received by a corresponding first recess (not shown) of the second anti-rotation feature of the compressor housing 2. The first projection and first recess extend generally axially - i.e. parallel to the central / spring axis 32.

[0085] It will be appreciated that, in other embodiments, it may be the first anti-rotation feature of the wave retaining ring which comprises a recess that receives a corresponding projection of the second anti-rotation feature of the compressor housing.

[0086] In some embodiments, it may be possible to rotate the first turbo machine component 58 relative to the second turbo machine component 2 by hand. However, in other embodiments, the first turbo machine component 58 may include a tool engagement feature. The tool engagement feature is configured, in use, to engage with a rotation tool and transform a rotation of the rotation tool into rotation of the first turbo machine component 58 relative to the second turbo machine component 2 about said first axis. The tool engagement feature and corresponding rotation tool may take any appropriate form - for example, the rotation tool may include a plurality of radially extending projections which are angularly spaced about the axis. The radial projections maybe received in corresponding radially extending recesses provided in the plate member 58. All that is required is that the first turbo machine component includes a tool engagement feature which is sized and located to, in use, engage a corresponding portion of the rotation tool so that the rotation tool, when rotated, can transfer a torque to the first turbo machine component 58 to enable the first turbo machine component 58 to be rotated relative to the second turbo machine component.

[0087] As previously discussed, the wave retaining ring 72 is generally annular, extending around a central (ring) axis. An axial height h of the wave retaining ring oscillates as a function of angular position about the ring axis. Again, as previously discussed, the axial height h of a portion of the wave retaining ring may be the distance along the axis that said portion of the wave retaining ring is located with respect to a fixed datum point along the axis. Whilst the axial height h can be measured with respect to any fixed datum point along the axis, in some situations it may be advantageous for the chosen fixed datum point to be halfway between the maximum extent of the wave retaining ring along the axis in a first direction, and the maximum extent of the wave retaining ring along the axis in a second direction, opposite to the first direction. The wave retaining ring 72 has a plurality of crest portions 72b in which the axial height h of the wave retaining ring 72 is a maximum. In particular, in the wave retaining ring shown in Figure 7, there are three crest or peak portions. Similarly, the wave retaining ring 72 has a plurality of trough portions 72a in which the axial height h of the wave retaining ring 72 is a maximum.

[0088] Figure 6 shows two schematic views of the first turbo machine component: plate member 58. The plate member 58 is shown in the right view in plan (perpendicular to the central axis 32). The view on the left shows a schematic view of the portion of the plate member 58 circled in the right view. The view on the left is a view around the circumference of the portion of the plate member 58 where the circumference has been laid flat in the plane of the page. The left view is a view which runs parallel to the central axis 32. A feature which extends from top to bottom in the left figure is a feature which extends in an anticlockwise direction around the central axis 32 in the right view. Conversely, a feature which extends bottom to top in the left view is a feature which extends circumferentially around the central axis 32 in a clockwise direction around the central axis 32 in the right view. A feature which extends from left to right in the left view extends towards the viewer from the plane of the figure in the right view. Conversely, a feature which extends right to left in the view on the left extends parallel to the central axis 32 out of the plane of the figure in the right view in a direction away from the viewer.

[0089] As can be seen best in the view on the right of Figure 6, the first clamp surface 58b is annular and is located at a radially outer portion of the plate member 58. As previously discussed, the axial height H of the first clamp surface 58b changes as a function of angular position about the axis 32. The first clamp surface 58b includes a plurality of trough portions 58c. All of the trough portions 58c are visible in the view on the right of Figure 6, whereas only one of the trough portions 58c is visible in the view on the left of Figure 6. For completeness, Figure 7 also shows all of the trough portions 58c.

[0090] In the present embodiment the number of trough portions 58c is three. However, it will be appreciated that, in other embodiments, any appropriate number of trough portions maybe used.

[0091] The number of trough portions 58c of the plate member correspond to the number of crest portions 72b of the retaining ring 72. In other embodiments, where the number of portions of the plate member differs from three, the wave retaining ring used may have a number of crest portions which corresponds to the number of trough portions of the plate member.

[0092] Referring now to Figure 6 in combination with Figure 7, the upper view within Figure 7 shows the plate member 58 in an unclamped position relative to the compressor housing 2. It can be seen that each of the peak portions 72b of the wave retaining ring 72 is located within a corresponding trough portion 58c of the first clamp surface 58b and that the axial spacing between the second clamp surface 70a and first clamp surface 58b is an unclamped spacing A sufficient to accommodate the relaxed axial height of the wave retaining ring 72 located axially between the second clamp surface 70a and the first clamp surface 58b.

[0093] The lower view within Figure 7 shows a plate member 58 in a clamped position relative to the compressor housing 2. As previously discussed, the plate member 58 shown in the clamped position in the lower view of Figure 7 has been rotated in the direction R relative to the compressor housing 2 by an angle 0. In the clamped position of the plate member 58 each of the peak portions 72b of the wave retaining ring 72 is not located within a corresponding trough portion 58c of the first clamp surface 58b. The axial spacing B between the second clamp surface 70a and the first clamp surface 58b is a clamped spacing which is less than said unclamped spacing. In this way the first and second clamp surfaces 70a, 58b apply an axial load to the wave retaining ring 72 which axially compresses the wave retaining ring 72 so that it has a working axial height. The working axial height is less than the relaxed axial height of the wave retaining ring 72 when the wave retaining ring 72 is in a relaxed state in which it does not have an axial load applied to it. As previously discussed, axially compressing the wave retaining ring will cause the clamped wave retaining ring 72 to exert axial and frictional forces on the plate member and compressor housing to secure the plate member and compressor housing together.

[0094] As can be seen best in the left view of Figure 6, each trough portion 58c of the first clamp surface 58d adjoins a corresponding circumferentially extending ramp portion 58d of the first clamp surface 58b.

[0095] Each ramp portion 58d of the first clamp surface 58b adjoins a corresponding circumferentially extending summit portion 58e of the first clamp surface 58b. Each summit portion 58e has an axial height H which is greater than the axial height H of the trough portion 58c of the first clamp surface 58b to which said summit portion 58e corresponds. Furthermore, each ramp portion 58d of the first clamp surface 58b is located circumferentially between the corresponding trough portion 58c of the first clamp surface 58b and the corresponding summit portion 58e of the first clamp surface 58b.

[0096] In the present embodiment, the ramp portions are generally linear - that is to say that their gradient (as a function of circumferential position) is constant. In other embodiments this need not be the case - for example, the gradient of the ramp portions may be non-constant such that the ramp portions have a generally curved profile. The ramp portions may be generally concave, generally convex or a combination of the two. Alternatively, the ramp portions may have a profile which is a combination of linear and either concave or convex.

[0097] In the presently described embodiment the trough portions, ramp portions, and summit portions of the first clamp surface are all identical. In other embodiments, this may not be the case. For example, each of these portions may have different circumferential lengths and / or different axial heights.

[0098] In the present embodiment the summit portions all comprise a plateau which extends circumferentially and is at a constant axial height H. A benefit of this arrangement is that the axial height H of the summit portions can be chosen so that it corresponds to an axial spacing between the clamp portions which compresses the wave retaining ring to an extent which produces a desired clamping force between the first and second turbo machine components. This gives positioning tolerance regarding the rotational position of the first turbo machine component relative to the second turbo machine component - provided the first turbo machine component is rotated to an angular position relative to the second turbo machine component such that the crests of the wave retaining ring are located on a portion of a corresponding summit portion of the first clamp surface, then the desired axial spacing between the first and second clamp surfaces, and hence the desired axial compression of the wave retaining ring (and hence desired clamping force due to the wave retaining ring) will be achieved.

[0099] In other embodiments the first clamp surface may not include summit portions. In this way, rotating the first turbo machine component relative to the second turbo machine component will cause the crest portions of the wave retaining ring to move along the clamp portions. The angular position of the first turbo machine component relative the second turbo machine component will determine the axial spacing between the first and second clamp surfaces and hence the amount of axial compression of the wave retaining ring, and hence the clamp force exerted by the wave retaining ring on the first and second turbo machine components. In this manner it is possible to, by choosing a particular angular position of the first turbo machine component relative to the second turbo machine component, set a desired clamping force exerted by the wave ring retaining member on the first and second turbo machine components.

[0100] The described and illustrated embodiments are to be considered as illustrative and not restrictive in character, it being understood that only preferred embodiments have been shown and described and that all changes and modifications that come within the scope of the inventions as defined in the claims are desired to be protected. In relation to the claims, it is intended that when words such as "a," "an," "at least one," or "at least one portion" are used to preface a feature there is no intention to limit the claim to only one such feature unless specifically stated to the contrary in the claim. When the language "at least a portion" and / or "a portion" is used the item can include a portion and / or the entire item unless specifically stated to the contrary.

[0101] Optional and / or preferred features as set out herein may be used either individually or in combination with each other where appropriate and particularly in the combinations as set out in the accompanying claims. The optional and / or preferred features for each aspect of the invention set out herein are also applicable to any other aspects of the invention, where appropriate.

[0102] Although the present invention has been described above in relation to a turbocharger, and, in particular in relation to securing a first turbocharger component (plate member) to a second turbocharger component (compressor housing), it will be appreciated that the invention applies equally to securing any appropriate first and second components together which form part of any type of turbo machine. Examples of turbo machine include a turbocharger, a turbine, a compressor, an e-turbocharger, an e-turbine, e- compressor and a power turbine. In general terms, a turbo machine is any machine that transfers energy between a rotor and a fluid - i.e. from a rotor to a fluid, or from a fluid to a rotor. Examples of appropriate first and second components which may be secured together in accordance with the invention include: a vaned ring component (also referred to as a nozzle ring) and a turbine housing; or a heat shield and a bearing housing.

Claims

CLAIMS:

1. A turbo machine assembly comprising: a first turbo machine component; a second turbo machine component; a wave retaining ring which frictionally secures the first turbo machine component to the second turbo machine component via clamping of the wave retaining ring between a first clamp surface of the first turbo machine component and a second clamp surface of the second turbo machine component; wherein the first turbo machine component is rotatable relative to the second turbo machine component about a first axis; and wherein an axial height of the first clamp surface changes as a function of angular position about the first axis; and wherein an axial spacing between a portion of the second clamp surface and the first clamp surface changes as the rotational position of the first turbo machine component relative to the second turbo machine component changes.

2. A turbo machine assembly according to claim 1 , wherein the wave retaining ring comprises a first anti-rotation feature which co-operates with a corresponding second anti-rotation feature of the second turbo machine component to substantially prevent rotation of the wave retaining ring relative to the second turbo machine component, when the first turbo machine component is rotated relative to the second turbo machine component.

3. A turbo machine assembly according to claim 2, wherein the first anti-rotation feature comprises a first projection which is received by a corresponding first recess of the second anti-rotation feature.

4. A turbo machine assembly according to claim 2, wherein the first anti-rotation feature comprises a first recess which receives a corresponding first projection of the second anti-rotation feature.

5. A turbo machine assembly according to claim 3 or claim 4, wherein the first projection and first recess extend generally axially.

6. A turbo machine assembly according to claim 3 or claim 4, wherein the first projection and first recess extend generally radially.

7. A turbo machine assembly according to any preceding claim, wherein the first turbo machine component comprises a tool engagement feature which is configured, in use, to engage with a rotation tool and transform a rotation of the rotation tool into rotation of the first turbo machine component relative to the second turbo machine component about said first axis.

8. A turbo machine assembly according to any preceding claim wherein the wave retaining ring is generally annular about a central spring axis and wherein an axial height of the wave retaining ring oscillates as a function of angular position about the spring axis, such that the wave retaining ring has one or more peak portions in which said axial height of the wave retaining ring is a maximum.

9. A turbo machine assembly according to claim 8, wherein the axial height of the first clamp surface changes as a function of angular position about the first axis and comprises one or more trough portions corresponding in number to said one or more peak portions, and wherein, in an unclamped position of the first turbo machine component relative to the second turbo machine component, each of the one or more peak portions locate within a corresponding trough portion of the first clamp surface and an axial spacing between said portion of the second clamp surface and the first clamp surface is an unclamped spacing sufficient to accommodate the axial height of the portion of the wave retaining ring located axially between the portion of the second clamp surface and the first clamp surface.

10. A turbo machine assembly according to claim 9, wherein, in a clamped position of the first turbo machine component relative to the second turbo machine component, in which, in relation to the unclamped position, the first turbo machine component is rotated about the first axis relative to the second component, each of the one or more peak portions of the wave retaining ring is not located within a corresponding trough portion of the first clamp surface and an axial spacing between said portion of the second clamp surface and the first clamp surface is a clamped spacing, less than said unclamped spacing, suchthat the first and second clamp surfaces apply an axial load to the wave retaining ring which axially compresses the wave retaining ring so that it has a working axial height which is less than a relaxed axial height of the wave retaining ring when the wave retaining ring does not have an axial load applied to it.

11. A turbo machine assembly according to claim 9 or claim 10, wherein each trough portion of the first clamp surface adjoins a corresponding circumferentially extending ramp portion of the first clamp surface.

12. A turbo machine assembly according to claim 11 , wherein each ramp portion of the first clamp surface adjoins a corresponding circumferentially extending summit portion of the first clamp surface, wherein each summit portion has an axial height which is greater than the axial height of the trough portion of the first clamp surface to which said summit portion corresponds, and wherein each ramp portion of the first clamp surface is located circumferentially between the corresponding trough portion of the first clamp surface and the corresponding summit portion of the first clamp surface.

13. A turbo machine assembly according to any proceeding claim wherein the first turbo machine component is a compressor outlet diffuser vane ring and the second turbo machine component is a compressor housing.

14. A turbo machine assembly wave retaining ring, wherein the wave retaining ring is generally annular about a central spring axis and wherein an axial height of the wave retaining ring oscillates as a function of angular position about the spring axis, wherein the wave retaining ring comprises a first anti-rotation feature for co-operating with a corresponding second anti-rotation feature of a turbo machine component to substantially prevent relative rotation between the wave retaining ring and the turbo machine component, and wherein the first anti-rotation feature comprises a generally radial protrusion and / or a generally axial protrusion.

15. A method of assembling a turbo machine assembly, the turbo machine assembly comprising: a second turbo machine component having a second clamp surface; a first turbo machine component rotatable relative to the second turbo machine component about a first axis, the first turbo machine component including a first clamp surface having an axial height which changes as a function of angular position about the first axis; and a wave retaining ring; wherein the method comprises: locating the wave retaining ring between the first clamp surface and second clamp surface; rotating the first turbo machine component relative to the second turbo machine component to change the rotational position of the first turbo machine component relative to the second turbo machine component and thereby reduce an axial spacing between a portion of the second clamp surface and the first clamp surface, and hence clamp the wave retaining ring between the first turbo machine component and second turbo machine component and thereby frictionally secure the first turbo machine component to the second turbo machine component.

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